This invention is related to two piece seal rings for valves employing nonmetallic seal elements. In the past, many composite valve seal constructions have employed a combination of separate rings to form a seal ring that is either carried by the body of a valve or by an insertable seat ring. These valve seal constructions usually include a non-metallic element and a metallic element or two non-metallic elements which are retained in the valve body or the valve seat ring by mechanical pressure only. The patent of E. H. Vickery, U.S. Pat. No. 3,077,902 issued Feb. 19, 1963, illustrates metallic and non-metallic seal elements retained in the valve by pressure exerted on them by a removable ring that is secured by fasteners or bolts. The patent of Grove et al, U.S. Pat. No. 3,765,647 issued Oct. 16, 1973, illustrates a pair of non-metallic seal elements which are secured in the groove by a lip portion of the seat ring which is bent or rolled over a portion of one of the elements during the manufacture. In this latter construction, a cement or bonding agent is applied to the adjoining surfaces of the two seal rings and the supporting structure prior to bending the lip over the inner seal ring.
The major difficulties with sealing assemblies of the type shown in the Grove patent are obtaining a good dependable bond between the sealing elements and bending the lip. Also, due to the generally circular cross-section of the seal member adjacent to the lip a very elaborate technique must be utilized to retain the seal element in place as the lip is being bent without the seal element escaping due to the lubrication of the cement. This type of difficulty makes this seat very expensive to manufacture.